Question

state and explain​ hess,s law of constant heat summation with suitable example.what are it,s application​

Answer 1

Explanation:

It states that

"Overall the enthalpy change for a reaction is equal to sum of enthalpy changes of individual steps in the reaction".

Ex:

1. 2H2 + N2 gives N2H4. ∆H=+95.4KJ
2. N2H4 + H2 gives 2NH3. ∆H=-187.6KJ

3H2 +H2 gives 2NH3. ∆H=-92.2KJ---eqn3

eqn3 gives total enthalpy change of reaction.

APPLICATION:

The Hess's law has been usefull to calculate the enthalpy changes for the reactions with their enthalpies being not known experimentally.